Salt Institute: www.saltinstitute.org
This page is available here: http://www.saltinstitute.org/14.html
Excerpt:
Salt occurs naturally in underground deposits, and occasionally in surface deposits in arid areas, as the mineral halite. Ancient salt deposits are widespread. There are ten major salt basins in the western hemisphere, in both North America (for example, Michigan 1 2 3 and New York) and South America ( 1 2 ) as well as deposits around the world (see, for example, the salt-related geology in Germany).